#!/usr/bin/python3

# Ramdomize the lines from stdin.
#
# Uses a stronger source of entropy, so you don't end up with repeated output
# (or at least repeated starts# so often as with sort -R or
#  perl -MList::Util # -e 'print List::Util::shuffle <>'
#

# Copyright (c) 2015 Peter Palfrader <peter@palfrader.org>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import argparse
import random
import sys

parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('-s', '--sample', metavar='LINES', type=int, nargs='?', const=1, help='Print only this many lines (1).')
args = parser.parse_args()

lines = sys.stdin.readlines()

r =  random.SystemRandom()
if args.sample is None:
  r.shuffle(lines)
else:
  lines = r.sample(lines, args.sample)

for l in lines:
  print(l, end='')